1. Field of the Invention
The subject invention relates to an antenna system. More specifically, the invention relates to a circularly polarized antenna for use with the system.
2. Description of the Related Art
Motor vehicles have traditionally been equipped to receive RF signals, particularly terrestrial broadcast signals, i.e., AM and FM radio broadcasts. Recent technological advances have created a need for reception of other RF signals, such as cellular (mobile) telephone signals, Satellite Digital Audio Radio Service (SDARS) signals, and global positioning system (GPS) signals.
To receive circularly polarized signals, such as SDARS or GPS signals, patch antennas have been used. However, these patch antennas often require that radiating elements include specialized perturbation features to generate the circular polarization with practical implications which can affect antenna performance. In order to improve reliability and performance, as well as reduce cost and create more desirable aesthetics, it is desirable to have a circularly polarized patch antenna with minimal or no perturbation features. Furthermore, prior art patch antennas often include wire feed lines which must be directly connected, i.e., soldered, to the patch antenna. Soldering a feed line to the patch antenna is impractical for certain antenna implementations as well as being a labor intensive process which often results in antenna defects. Moreover, when the antenna is implemented with a vehicle window, the vibration of the window can effect solder joints as well as having other adverse effects.